1. Field of the Invention
The present invention relates generally to a mobile communication system, and more particularly, to a method and apparatus for providing voice calls in a heterogeneous mobile communication system and a system thereof.
2. Description of the Related Art
A mobile communication system has been developed that allows users to communicate without geographic restriction. Such a mobile communication system has evolved from an early system that provides only the simple voice communication services into an advanced system that can provide high-speed data services, and packet-based voice services such as Voice Over Internet Protocol (VoIP).
In addition, the mobile communication system has developed from a Circuit Switching (CS) system that provides basic voice services and lower-speed data services, to a Packet Switching (PS) system that offers high-speed packet data services. The CS-based mobile communication system may include a 2nd Generation (2G) system and a 3rd Generation (3G) system. The 3G system may provide higher-speed data services. Because many users desire to receive much higher-speed data services, there is an increasing need for systems that have progressed from the 2G and 3G systems. To meet the need, a Long Term Evolution/System Architecture Evolution (LTE/SAE) system is currently under development.